In a pediatric girl with acute rheumatic fever after recent streptococcal pharyngitis, which prophylaxis will prevent recurrence?

Secondary Prophylaxis for Acute Rheumatic Fever

Benzathine penicillin G administered intramuscularly once monthly (Option B) is the correct answer and gold standard for preventing recurrence of acute rheumatic fever in this patient.

Clinical Context

This pediatric girl presents with classic acute rheumatic fever (ARF) following group A streptococcal pharyngitis—left knee arthritis with swelling, chest pain on exercise (suggesting carditis), and a preceding sore throat three weeks ago. 1 The latency period of 2-3 weeks between pharyngitis and ARF manifestations is characteristic. 2, 3

Note: The initial treatment with corticosteroids for her sore throat was inappropriate—streptococcal pharyngitis requires antibiotics, not steroids alone. 1

Why Benzathine Penicillin G Monthly is Superior

Intramuscular benzathine penicillin G provides approximately 10 times greater protection than oral antibiotics, with recurrence rates of 0.1% versus 1% for oral regimens (relative risk 0.07,95% CI 0.02-0.26). 4, 5

The recommended regimen is:

• 1,200,000 units intramuscularly every 4 weeks for patients ≥27 kg 4
• 600,000 units intramuscularly every 4 weeks for patients <27 kg 4
• In high-risk populations (children, economically disadvantaged, or those with recurrence despite 4-week dosing), administer every 3 weeks 4, 5

Why Other Options Are Incorrect

Option A: 10-Day Oral Penicillin

This represents primary treatment of acute streptococcal pharyngitis to prevent initial ARF, not secondary prophylaxis. 1, 4 While a 10-day course should be given immediately to eradicate residual streptococci even if throat culture is negative, this is a one-time treatment, not ongoing prevention. 1, 3 Continuous prophylaxis is required because ARF recurrence can occur even when symptomatic GAS infections are treated optimally, and many triggering infections are asymptomatic. 1, 2

Option C: Streptococcal Vaccine

No streptococcal vaccine is available for clinical use. 3 This is not a valid treatment option.

Option D: Influenza Vaccine

Influenza vaccine has no role in preventing ARF, which is caused by group A streptococcus, not influenza virus. 1 While viral pharyngitis can mimic streptococcal pharyngitis, influenza vaccination does not prevent streptococcal infections or ARF recurrence.

Duration of Prophylaxis

The duration depends on cardiac involvement, which must be assessed immediately with clinical examination and echocardiography: 1, 3

• No carditis: 5 years or until age 21 (whichever is longer) 1, 2
• Carditis without residual valvular disease: 10 years or until age 21 (whichever is longer) 1, 2
• Carditis with residual valvular disease: 10 years or until age 40 (whichever is longer), often lifelong 1, 4, 2

Given this patient's chest pain on exercise, immediate echocardiography is essential to detect carditis and determine prophylaxis duration. 2, 3

Critical Management Points

Patients with previous ARF are at extremely high risk for recurrent attacks when GAS pharyngitis develops, with each recurrence potentially worsening rheumatic heart disease. 1, 2 The GAS infection need not be symptomatic to trigger recurrence. 1, 2

All household contacts should have throat swabs obtained and positive contacts treated regardless of symptoms to prevent transmission. 2, 3

Common Pitfalls

• Never rely on oral antibiotics alone for secondary prophylaxis—compliance is poor and protection is inadequate. 4, 5
• Do not stop prophylaxis prematurely—this puts patients at high risk for recurrence with subsequent streptococcal infections. 3
• Do not delay cardiac evaluation—subclinical carditis may be missed without echocardiography, affecting both prognosis and prophylaxis duration. 2, 3